High levels of arsenic, lead found beneath Tennessee Valley Authority plant

A pond sits just east of the Allen Power Plant where the Tennessee Valley Authority found high levels of arsenic and other toxins in ground water underlying the plant where thousands of tons of coal ash are impounded.(Photo: Jim Weber/The Commercial Appeal)Buy Photo

The Tennessee Valley Authority found high levels of arsenic and other toxins in ground water underlying a Southwest Memphis power plant where thousands of tons of coal ash are impounded, the agency told state regulators.

The arsenic, measured at levels more than 300 times the federal drinking-water standard, was discovered in monitoring wells at the Allen Fossil Plant. Excessive amounts of lead also showed up in the 50-foot-deep wells that were installed to check for any pollution emanating from ponds containing ash and boiler slag generated by burning coal.

The tainted ground water lies within a half-mile of where TVA recently drilled five 650-foot-deep wells into the Memphis Sand aquifer, the source of local drinking water, from which it plans to pump 3.5 million gallons daily to cool a natural gas-fueled power plant under construction. Local scientists and environmentalists had opposed the wells, saying the pumping could pull contaminants into the Memphis Sand.

"We are confident the contaminants found in TVA wells at the Allen Fossil Plant are not impacting drinking water. Out of an abundance of caution, we have requested Memphis Light, Gas and Water (Division) to sample its treated water in order to give that assurance to customers," TDEC spokesman Eric Ward said in an email.

The pollution turned up in analyses of water from several monitoring wells at or near the plant. In three of the wells, arsenic levels were consistently above the drinking-water standard of 10 parts per billion, with concentrations in one well surpassing 3,000 parts per billion. The testing also turned up lead concentrations two to four times higher than the drinking water standard in one well.

MLGW President and CEO Jerry Collins said that in response to the request by TDEC the utility has begun testing wells serving its Davis Water Treatment Plant, located about three miles southeast of the Allen facility, for signs of the contaminants. Water samples have been sent to a laboratory for analysis, he said, but the results aren't back yet.

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"I don't anticipate any problems...," Collins said. "There's no reason for the public to be alarmed."

Still, Shelby County Mayor Mark Luttrell called the arsenic contamination "unacceptable to our community," and University of Memphis researcher Brian Waldron, a major critic of TVA's plans to tap the Memphis Sand for cooling water, said the pollutants could reach drinking-water supplies through several means. The arsenic could seep through breaches in a protective clay layer above the Memphis Sand or trickle into surface water near MLGW's well fields, he said.

"This is why I've been saying no one should be pumping" in the area of the new TVA plant, said Waldron, who is director of the Center for Applied Earth Science and Engineering Research at U of M.

After being notified of the arsenic levels in a May 19 email, state officials sent a letter to TVA last month requesting its "full cooperation" in launching a deeper investigation to determine the source and extent of the contamination. As part of that effort, TVA will be installing additional monitoring wells, as well as reporting to TDEC by the end of this week all results of previous soil and ground-water testing at the site.

TVA spokesman Scott Brooks said the agency is cooperating with TDEC. The discovery of the pollution, however, won't affect the agency's plans to pump water from the Memphis Sand to cool the natural gas-fired, $975 million Allen Combined Cycle Plant, which is set to replace the nearby coal-burning plant in June 2018, he said. The shallow aquifer in which the contaminants showed up is not connected to the shallow and above the dense clay over Memphis Sand.

"The wells that were tested don't go below the clay barrier," Brooks said.

TVA so far hasn't determined whether the arsenic and lead seeped from the ash ponds, he added. "We don't know where it's coming from."

For decades, TVA has managed the millions of tons of ash, slag and other combustion residue generated each year by its coal-fired plants — including the 58-year-old Allen facility — in on-site ponds protected by earthen dikes or berms.

The ash, which can contain arsenic, lead and other toxic substances, is piped with water into ponds where heavy metals settle to the bottom and cleaner water at the top is released after being tested to ensure it meets pollution standards.

The ponds have posed a growing concern for TVA and environmental regulators ever since a catastrophic dike failure at the agency’s Kingston Fossil Plant in East Tennessee in 2008 unleashed a 1.1 billion-gallon toxic deluge, damaging nearby homes and poisoning rivers. In the aftermath of the spill, TVA made a commitment to convert wet ash ponds to safer dry ones.

With TVA now set to retire Allen and several other coal-fired facilities — replacing them with cleaner gas-burning power plants — the agency is required by state and federal regulators to conduct environmental studies the ash ponds.

TVA has explored various options for closing the ponds. Officials have said they prefer capping the ash in place under a waterproof barrier rather than excavating it and hauling it to landfills. Despite the newly found contaminants, Brooks said, "it's too early to say whether it will change the way we move forward."